Vectored Blood Stage Malaria Vaccine

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Malaria is one of the greatest causes of infectious mortality globally but no vaccine is available. The blood-stage of the parasite?s life-cycle is the one that causes all the symptoms of disease and very often death. Many vaccines against this stage have been tested in clinical trials but always with disappointing results. However, all these vaccine comprised protein components of the parasite mixed with a chemical adjuvant designed to try and increase the immune response to the vaccine. Quite different types of vaccine are now showing promise in other diseases such as HIV/AIDS, tuberculosis and even the liver-stage of malaria. These vectored vaccines use a crippled safe virus to produce the malaria antigen inside the injection site of the vaccinee. This generates qualitatively and quantitatively different immune responses to protein/adjuvant vaccines. Using a rodent malaria model we have found excellent protection using such vectored vaccines against blood-stage malaria and have gone on to make the corresponding vectors that target the major human parasite Plasmodium falciparum. In this application we propose to test a pair of vectored vaccines against the blood-stage of malaria for the first time in humans. We will use a well developed and safe infectious mosquito biting procedure to test whether the vaccine is effective in volunteers. This study should provide a critical test of the possibility that such vectored vaccines could be useful in protecting people against the important blood-stage of malaria.